Mineral dye and method of making same



Patented Aug. 31, 1937 PATENT OFFICE MINERAL DYE AND METHOD OF MAKING SAME Clarence B. White, Montclair, N. J.

No Drawing.

Application January 14, 1935.

Serial No. 1,701

'1 Claims.

prising essentially one or more chromium saltsof carbohydrate acids and being especially suitable for use either singly or in admixture with additional ingredients for dyeing or for printing textile materials and the like.

Heretofore, the only compound of chromium that could be satisfactorily used in mineral dyeing of textile materials was chromous acetate and the use of this compound was attended with serious obstacles, among which may be mentioned, the following; firstly, chromous acetate can only be completely precipitated, as chromic hydroxide among the fibres of the textile material treated, after long continued boiling with caustic alkali, a condition which renders mass production impossible and results in the bleeding or dispersion of a portion of the'chromous acetate, thereby weakening the resulting shade of the textile material and rendering such shade variable or smeary; secondly, to. avoid variations in shade it is necessary to put the dye saturated textile material through a highly expensive aging process during which the textile material is treated with a mixture of high pressure steam and atmospheric oxygen in an ager, wherein the chroao mous salt is partially hydrolyzed and oxidized to a chromic condition, in which state it is much more rapidly reactive in the presence of caustic alkalies; and thirdly, chromous acetate can only be obtained in a condition of limited concentration when in solution, 1. e. about seven percent of chromium oxide, and this concentration is not suflicient for the production of a deep, or heavy shade in one passage of the textile material through the dye liquor and hence it is necessary to resort to multiple dyeing when such a shade is desired, thereby making it very diflicult or even impossible to match shades. 4

Attempts have been made to use other compounds of chromium in mineral dyeing, i. e. the more soluble chromic salts such as the nitrate, chloride, and sulphate of chromium, but these have not proven practicable because of the tendency of the chromium salts to hydrolyze and set free the acid ions which in turn tender the fabric. This tendency, while it renders chromium salts invaluable as mordants in the dyeing of wool, at

the same time causes them to be useless in the dyeing of cotton. When a cotton fabric thus impregnated is dried on the cans, the chromic sul- 5 phate or chloride is decomposed, and sulphuric or hydrochloric acid, as the case may be, is liberovercome the-above recited disadvantages of the known compounds of chromium, i. e. the compounds of this invention are sufficiently soluble to permit a concentration great enough to insure the proper depth of shade with'but a single dyeing so that even or matched shades are-readily obtained; the compounds of this invention are sufficiently reactive to the insolubilizing medium to permit the formation of the insoluble chrome dyeing compound immediately on contact with the insolubilizing bath, without bleeding out in the bath, thereby eliminating the customary expensive aging process; and the compounds of this invention do not hydrolize, i. e. set free acid ions to disintegrate the fabric when the same is dried on the cans.

Another object of the present invention lies in the provision of a novel chromium dye composition of the above character that is miscible with iron and other metallic salt dye liquors and which will not precipitate any such salts with which it is mixed, the said composition being sumciently stable when used alone or in conjunction with other mineral dye liquors, so that no precipitation or. clodding, or the formation of insoluble residues shall take place before or during the application of the dye liquor to the fabric bein processed.

Still another object of the present invention is to provide a novel dye composition of the above character that may be easily and cheaply produced on a production basis.

Other objects of this invention, not at this time more particularly enumerated. will be understood from the following detailed description 01' the same.

The novel composition of this invention comprises one or more chromium salts of such carbohydrate acids as gluconic, saccharic and mucic, and/or saccharosa'tes, i. e. compounds of sugar and metallic oxides. These compounds can be readily prepared in a condition of great concentration, exceeding in some cases a content of 20% chromic oxide equivalent. I preferably use either sodium bichromate or potassium bichromate as a raw material from which the chromium salts are prepared, the sodium bichromate being especially suitable owing to its relative cheapness.

In carrying out the process of the present invention, I dissolve or mix a carbohydrate such as starch, dextrine, cane sugar or corn syrup in water to which three to five percent 61' acid, preferably hydrochloric or sulphuric, isadded, after which the whole is digested at a temperature exceeding 70 C. until the carbohydrate has been hydrolyzed intoa monosaccharide or'simple sugar. Preferably a portion of the monosaccharlde is nowoxidized to saccharic acid by the addition of nitric acid or equivalent oxidizing agent. However, if desired, the production of the necessary saccharic and gluconic acids may be left to the oxidizing action of chromium trioxide set free in the manner hereinafter described. The presence of an excess of saccharic acid above the quantity necessary to form a saccharate or similar compound with the whole of the chromium to be added is desirable, although not indispensable, and I therefore prefer to oxidize a portion of the monosaccharide present,"

allowing sufllcient reducing sugar in the solution to effect the reduction of the chromic compounds derived from the alkaline bichromate.

Additional acid, preferably sulphuric .or hydrochloric, is now added to the solution containing the hydrolyzed carbohydrates in. amount suificient (molecular proportion) to break down the alkaline bichromate to be later added. The alkaline bichromate is now added to the acidulated monosaccharide solution in small portions at a time, thereby preventing loss through excessive foaming, the corresponding salt of the alkali and the acid used in its reduction being formed along with chromium trioxide in accordance with the following formula:

40 As a specific example of the actual manufacture of the mineral dye composition of this invention, the following ingredients are employed in the proportions given by weight:-

45 Pounds Cane sugar, dextrine, starch or corn syrup--- 125 Water"- 620 Sulphuric acid '100 Sodium bichromate 300 50 In carrying out the process of manufacture of the dye composition, I add 35 lbs. of sulphuric acid (or its molecular equivalent of hydrochloric acid) to 620 lbs. of water (75 gallons) and into this acid solution I mix or dissolve 125 lbs., of any 55 one of the substances, cane 'sugar, dextrine,

starch, corn syrup, or other suitable carbohydrate compound. I then heat the resulting solution to a temperature of at least 70 C. and maintain the temperature at this figure or above 60 until the carbohydrate has been hydrolyzed and converted into monosaccharide or simple sugar compound. The time required for this conversion will vary according to the nature of the hydrocarbon used as the basic raw material, be-

5 ing relatively long in the case of starch (one to three hours) and much shorter in the case of cane sugar.

I now preferably, though not necessarily, oxidize a portion of the monosaccharide by the 70 addition of a small quantity of nitric acid in accordance with the following equation:-

'l now add 65 lbs. of sulphuric acid and heat 7 the mixture to at least 88 C. after which I add 300 lbs. of bichromate of sodium (or its equivalent in another alkaline bichromate). The sodium bichromate is added gradually, care being taken in making these additions so that no violent rise in temperature takes place such as 5 would cause the liquid to boil violently, thereby resulting in loss of material. It is desirable that the temperature be maintained at as high a point as possible, but violent ebullition and consequent foaming of the liquid is to be avoided. 10 The reaction unless controlled, is exceedingly violent and at the same time strongly exothermic, making it possible to control the temperature within a desired range by the judicious addition of the alkaline bichromate, care being taken to 15 distribute the latter evenly in the bath. As the reaction approaches its close, the temperature rise after each addition ofalkaline bichromate becomes progressively less, until it finally becomes necessary (in general) to apply external 20 heat in order that the reaction may not become arrested and the alkaline bichromate fail to be completely reduced. Lack of complete reduction of the alkaline bichromate causes the mixture to take on a brown color, whereas complete 25 reduction results in the mixture or reduced liquor having a decidedly green color.

When the operation is definitely completed the resulting dye liquor will contain an alkaline sulphate or chloride or an alkaline salt of the acid used to decompose the bichromate compounds, together with the chromium contents of the alkaline bichromate as a carbohydrate compound of chromium, i. e. as a gluconate such as chromium gluconate Cr2(CcH11O1)e, or as a saccharate such as chromium saccharate Cl2(CcHaOs) a, or/and a compound of chromic oxide and saccharose. i. e. chromium saccharosate, all of which are soluble. The dyeing liquid is very weakly ionized and even if hydrolyzed exerts no damaging effect 40 upon cellulose, whichis also a carbohydrate.

If desired, the sodium bichromate may be dissolved in water before mixing with the acid-sugar solution. For example, the 300 lbs. of sodium bichromate'may be dissolved in 620 lbs. of water (75 gals.) and the whole heated to 88 C., whereupon the acid-sugar solution which has previously been heated to approximately 70 C. is slowly added to the alkaline bichromate solution, care being taken that the temperature shall not rise with acid-saccharine solution until the color has become permanently green. It is necessary to maintain the intermixed solutions at as high a temperature as possible during the whole of the rev action. The reaction is facilitated by the presence of saccharic acid, which acid is easily produced by the addition of a quantity of nitric acid to a portion of the saccharine liquid.

The novel mineral dye solution 'thus produced may be diluted with water as desired to give various shades of green and even the deepest shades can be applied with but a single immersion and padding of the, textile material. The chromium carbohydrate salt or' salts of the dye solution being already in an oxidized condition,,7o require no further oxidation when padded into the fabric to be dyed. Also, these chromium carbohydrate salts react rapidly with caustic alkali, becoming immediately insolubilized, and without the bleeding or solution of the san. Ii

in the precipitating medium orhot caustic soda bath, which is the case with most salts of chromium. The cellulose or cotton of the textile material being a carbohydrate does not react chemically with these carbohydrate compounds of. chromium, and consequently there is no tendency to tender or disintegrate the fabric as is the case when inorganic acid compoundsare utilized. As a matter of fact, glucose, sucrose, and most saccharate compounds exert a protective influence against the attack of free mineral acids on cellulose structure, and while not actually inhibiting such action, at least greatly delay the formation of oxycellulose and hydrocellulose in the presence of such acids.

In order to dye a variety of colors the dye composition of the present invention may be intermixed with other dye materials such as pyrolignate of iron or salts of manganese thereby obtaining such additional colors as pearl, "battleship grey", "sand shades, "Hong Kong", khaki and "buff", iron pyrolignite being used for this purpose because of its inertness to cellulose. The carbohydrate compounds of chromium have a very low hydrogen ion concentration and hence do not tender fabrics while at the same time their acid radical is readily replaced by acid radicals such as those of sulphuric and hydrochloric acids. It -is, therefore, possible without danger of tendering the fabric to replace a part of the iron pyrolignite by such iron compounds as ferrous sulphate and ferric sulphate, or ferric chloride, thereby greatly lowering the cost of the mineral dye liquor and even improving its quality.

The following are typical dye mixtures using the chromium carbohydrate compounds of this invention:

Pearl" or battleship grey.

4o Aqueous solution of carbohydrate compound of chromium (i. e. such as chromium saccharate) 10 to 20% chromic oxide content.-

- "Khaki (all ingredients on basis of 5% oxide).

Gals.

Chromium carbohydrate compound 25 Iron pyrolignite 37% Ferrous or ferric sulphate solution 37 Chromium compound solution 25 Iron pyrl'lliirnifl 75 The novel chromium carbohydrate compounds of this invention, when in the presence of a reducing agent such as glucose, sodium hydrosulphide, thiosulphate, etc., exert a distinct solvent action on certain so called "vat" dyestuffs, i. e. derivatives in general of anthracene and anthraquinone bases, thereby making it possible to introduce such dyestufls directly into the mineral dye solution, whether composed entirely of chromium compounds or chromium compounds in admixture with salts of iron. The introduction of these dyestufls enables the production of a great 85 variety of shades, of which the majority are very fast to light, alkali and exposure. In use, the mineral dye liquor carrying a certain proportion of vat dyestuii' is padded directly on the fabric, squeezed and dried, the anthracen'e dyestuif being 70 oxidized and fixed upon the fabric in an insoluble condition during the drying operation. The chromium content of the dyed fabric is then insolubilized in the normal manner, i. e. by passing the fabric through a hot bathof caustic alkali.

The dye composition of this invention may also be used in conjunction with the so-called sulphur. dyestuffs. The sulphur dyestuifs to be used, are 5 dissolved in the usual alkaline dye bath of sodium sulphide, care being taken to provide an excess of sodium sulphide with which to effect the insolubilization of the chromium compounds deposited on the fabric. In use, the fabric, to be dyed is 10 first impregnated in the bath of chromium salts, squeezed and dried. The dried fabric is then passed through the hot sulphide dye bath containing the sulphur dyestuffs in solution, and the latter are deposited upon and absorbed by the 15 fabric simultaneously with the insolubilization of the chromium compounds already padded into the fabrics. This operation can either be carried out in amordinary jigger" or as a continuous process of sulphur dyeing in the conventional box machine or sulphur dye run.

In the claims the word carbohydrate" covers that group of compounds containing carbon combined with hydrogen and oxygen according to the formula CeIHO) r, in which a: may be 5, 6 25 or 12, and u may be 5, 6 or 11.

- l. A mineral dye comprising a saccharose derivative of the group consisting of chromium gluconate and chromium saccharate. 30

2. A mineral dye liquor comprising an aqueous solution of a chromium salt of an acid formed by the oxidation of glucose by means of an alkali bichromate.

3. A mineral dye liquor comprising an aqueous 35 solution of a mixture of a saccharose derivative of the group consisting of chromium gluconate and chromium saccharate; and pyrolignite of iron.

4. A mineral dye liquor comprising an aqueous solution of a mixture consisting of chromium gluconate, pyrolignite of iron and sulphate of iron. V

5. The method of making a mineral dye comprising, mixing an alkali bichromate with an acidulated aqueous solution of a polysaccharide of the group consisting of cane sugar, corn syrup and dextrine, the amount I of acid being just suillcient to displace the alkali metal radical and without producing a chromium saltof the acid, care being taken to keep the temperature of the reacting mixture as high as possible without undue ebullition.

6. The method of making a mineral dye comprising, hydrolizing a carbohydrate to a monosaccharide of the glucose group, adding only sufllcient acid to the solution to produce gluconic acid without any salt of the acid used, heating the same, and gradually adding an alkali bichromate to the heated solution. so

7. The method of making a mineral dye comprising, mixing an alkali bichromate with a so-' iution of a polysaccharide oi the group consisting of cane sugar, corn syrupand-dextrine and sumcient acid to combine with the alkali metal com- .05 ponent, but not suflicient to form a salt of chromium with such acid, forming in such mixture simultaneously chromium trioxide and a carbohydric acid both of which unite to form a compound of chromium. 7o CLARENCE 3. WHITE. 

